From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 35E3AC61DF4 for ; Fri, 24 Nov 2023 13:07:43 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1r6VtV-0005NT-BX; Fri, 24 Nov 2023 08:06:54 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r6VtO-0005Ma-Fp for qemu-devel@nongnu.org; Fri, 24 Nov 2023 08:06:46 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r6VtM-0002ol-NZ for qemu-devel@nongnu.org; Fri, 24 Nov 2023 08:06:46 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700831202; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=1k96+Bz/Ulc8c/LKVi2bPrkQr96vvTSf4TdAO1Yo9SY=; b=G14EXvxdX+BV0X9EOJVFzjP9DbpULuOMA2OAADfG7kd6z7/NO6R9p3rCjtV3cRAtf4nkfF Q5qLCFrK5P6ym8EQMT8dmf35GcDGO1sB28m4B0y44VVIlvMTt1Vo/Max22kF2sKXarcqFU 4es40ZxmRnSPnid32jazeqxxUv2FJHY= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-219-JnWUT-D2P2SvlagYE7bKRA-1; Fri, 24 Nov 2023 08:06:41 -0500 X-MC-Unique: JnWUT-D2P2SvlagYE7bKRA-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id BE74D28AC1DD; Fri, 24 Nov 2023 13:06:40 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.59]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A9CE0492BFA; Fri, 24 Nov 2023 13:06:39 +0000 (UTC) Date: Fri, 24 Nov 2023 14:06:38 +0100 From: Kevin Wolf To: Dmitry Frolov Cc: hreitz@redhat.com, qemu-block@nongnu.org, sdl.qemu@linuxtesting.org, qemu-devel@nongnu.org Subject: Re: [PATCH] block/monitor: blk_bs() return value check Message-ID: References: <20231124113037.2477645-1-frolov@swemel.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231124113037.2477645-1-frolov@swemel.ru> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Am 24.11.2023 um 12:30 hat Dmitry Frolov geschrieben: > blk_bs() may return NULL, which will be dereferenced without a check in > bdrv_commit(). > > Found by Linux Verification Center (linuxtesting.org) with SVACE. > > Signed-off-by: Dmitry Frolov Do you have a reproducer for a crash? As far as I can see, it will not be dereferenced, because blk_is_available() returns false and we return an error before calling bdrv_commit(): QEMU 8.1.91 monitor - type 'help' for more information (qemu) info block ide1-cd0: [not inserted] Attached to: /machine/unattached/device[6] Removable device: not locked, tray closed floppy0: [not inserted] Attached to: /machine/unattached/device[16] Removable device: not locked, tray closed sd0: [not inserted] Removable device: not locked, tray closed (qemu) commit ide1-cd0 Device 'ide1-cd0' has no medium Kevin